Hydrocarbon recovery employing aqueous medium driving fluid having increasing viscosity

ABSTRACT

Hydrocarbons are recovered from a subterranean hydrocarbon containing formation by injecting an aqueous medium driving fluid through said formation to displace hydrocarbons therefrom. The aqueous medium driving fluid comprises a bacterial cellular solution that has been treated for providing a driving medium whose viscosity increases during displacement to the formation.

Unlted States Patent 1 3,650,326 Hitzman Mar. 21, 1972 54] HYDROCARBONRECOVERY 3,185,634 5/1965 Craig et a] ..166/275 x EMPLQYING AQUEOUSMEDIUM 3,251,417 5/1966 Holman et al.. ..l66/246 DRIVING FLUID HAVINGINCREASING $3 2 a 9 [72] Inventor: Donald 0. Hitzman, Bartlesville,Okla. FOREIGN PATENTS OR APPLICATIONS [73] Assignee: Phillips PetroleumCompany 654,809 12/1962 Canada ..l66/275 22 Filed: May 25, 1970 OTHERPUBLICATIONS [21] APPL 40,412 .lohansen, R. T., et a1., Detergents ForPetroleum Displacement In Soap & Chem. Spec., Oct. 1955, pp. 41- 44, 79,81. [52] US. Cl Primary Examiner-Stephen J, Novosad [51 Int. Cl. An0rney.Y ung and [58] Field of Search 1 66/246, 268, 273-275;

252/855 D; 195/31 P [57] ABSTRACT [56] References Cited Hydrocarbons arerecovered from a subterranean hydroearbon containing formatIon byll'lJCCIlng an aqueous medium UNITED STATES PATENTS driving fluidthrough said formation to displace hydrocarbons therefrom. The aqueousmedium driving fluid comprises a 3,372,749 3/1968 'WllllamS 1 66/275 Xbacterial cellular Solution that has been treated for providing 33,452,817 7/1969 Fallgatter 166/268 X i i medium whose viscosityincreases during displacement 3,302,713 2/1967 Ahearn et al. ....166/274to the formation 3,020,206 2/1962 Patton et al. ...195/31 P 3,491,8341/1970 11 Claims, No Drawings Aheam et a1. ..166/273 HYDROCARBONRECOVERY EMPLOYING AQUEOUS MEDIUM DRIVING FLUID HAVING INCREASINGVISCOSITY In conventional supplementary oil recovery operations,

such as secondary recovery and pressure maintenance operations, forexample, a fluid is injected into a subterranean hydrocarbon containingformation via at least one injection well to displace in-placehydrocarbons from the formation into a producing well where saidhydrocarbons are delivered to the surface and recovered. In a particularrecovery operation of this type, Water or brine is generally employedasthe aqueous medium driving fluid and the operation is referred to aswaterflooding.

While conventional waterflooding processes are effective in obtainingadditional hydrocarbons from a hydrocarbon containing subterraneanformation, it has a number of shortcomings. A primary shortcoming ofthis technique is the tendency of the flooding water to finger throughthe hydrocarbon containing formation and bypass substantial portions ofthe inplace hydrocarbons. By fingering is meant the developing ofunstable bulges or stringers which advance toward the produc' tion meansmore rapidly than the remainder of the flooding water. Furthermore, thewater does not normally displace as much hydrocarbons of the formationswhich it contacts as it is potentially capable of doing when fingeringoccurs. The net result is an inefficient hydrocarbon displacement actionon the part of the water.

Several methods havebeen suggested for improving the mechanics ofwaterflooding procedures, particularly with the view of reducing thedegree of fingering and bypassing, and the like. One suggestion has beento increase the viscosity of the water-drive medium relative to the oilby incorporating water soluble viscous agents within the water. Thematerials that have been suggested for this purpose include gums,polysaccharides, polymers, and the like.

While these additives are effective to some degree in increasing theviscosity of the flooding water, they have proven ineffective for avariety of reasons for oil recovery procedure. Many of these additivesform insoluble precipitants with ions contained either in the floodingwater or in the in situ fluids. Also, many of the aqueous solutions ofthese additives suffer severe reductions in viscosity when contactingthe brines, such as solutions containing sodium chloride or calciumchloride. Additionally, many of these materials are quite expensive andtheir use is not feasible from the standpoint of economics.

In order to avoid many of these heretofore experienced disadvantages inwaterflooding operations, a waterflooding process has been discoveredwhich utilizes an aqueous medium driving fluid comprising a bacterialcellular culture that has been treated to provide a driving fluid havinga viscosity which increases during displacement of that driving fluidthrough the formation.

In accordance with this invention, bacterial cells are treated withformaldehyde and are thereafter treated with an anionic surfactant forproviding a driving fluid having a characteristic of increasing theviscosity with the passage of time. This invention is particularlysurprising in that untreated whole bacterial cells are ineffectiveviscosifiers for employment in aqueous mediums as fluid drives forrecovering hydrocarbons, bacterial cells treated with nonionicsurfactants are likewise ineffective, and if a bacterial cellularculture solution is initially treated with an anionic surfactant theresultant mixture will produce a driving fluid initially having a highviscosity as opposed to the viscosity of the driving fluid-of thisinvention which has a relatively low viscosity that increases with thepassage of time.

The particular method used for providing the bacterial cultures employedin this invention is not critical so long as the bacterial culture isformed by growing said culture on a carbon source. It is preferred,however, that the most economical method to produce the largest quantityof bacterial cells in the least amount of time be used. Accordingly, asuitable fermentation medium is simply inoculated with the bacteria andsaid fermentation medium maintained under growth conditions to permitmultiplication of the bacterial cells. Carbon sources are provided andsuitable minerals, growth factors, vitamins, and the like are generallyadded in amounts sufficient to provide for the particular needs of thebacteria utilized. Substrate materials on which the bacteria is growncan be sugars, nparaffms, alcohols such as ethanol or methanol, andother carbonaceous materials can be employed. The fermentation reactionproduct, i.e., bacterial cells are then employed according to thisinvention by mixing them with formaldehyde and are thereafter treatedwith an anionic surfactant. The whole bacterial cells can be recoveredfrom the fermentation media after contacting them with formaldehyde ifdesired. In this case the cells are hereafter separated by, for example,centrifugation and thereafter treated in accordance with this invention.It is economically preferable, however, to eliminate bacterial cellseparation procedure and to merely treat the whole fermentation productsolution containing the bacterial cells.

The bacterial culture solution containing the bacterial cells can bediluted, if desired, by the addition of water or aqueous solutions suchas brine. They can be concentrated by the removal of water but it isimportant that the bacterial culture solution contains at least 0.2weight percent of bacterial cells. Bacterial culture solutionscomprising from about 2 to 4 weight percent of bacterial cells areroutinely produced. The volume of formaldehyde is generally in the rangeof about 0.1 to 5 weight percent, preferably about 1 weight percent ofthe cell solution.

About 5 minutes to 24 hours after mixing the bacterial and formaldehydemixture, an anionic surfactant is added to that mixture and theresultant viscosified aqueous medium driving fluid is injected into thehydrocarbon containing formation. The amount of time delay before addingthe anionic surfactant controls the time delay in the formation beforesubstantial in creases in viscosity occurs and is selected by theoperator to match the amount of viscosity increasing delay desired.

The surface agents employed according to this invention are anionicsurfactants. Compounds of this class are generally characterized asforming ions in solution and are typical colloidal electrolytes and arecharacterized in that upon ionization the ion containing the largehydrophobic group assumes a negative charge and becomes the anion. Thegeneral properties and behavior are generally attributed to the dualcharacter of the molecules of these substances in that they are made upof two parts, a relative large elongated part, the hydrophobic group anda small solubilizing, polar group, the hydrophilic group. Anionicsurfactants are widely known and commercially available. Mixtures ofanionic surfactants can also be employed according to this invention.Alkylarenesulfonates, sulfated alcohols, and the like are exemplaryclasses of anionic surfactants. Exemplary anionic surfactants that canbe employed are propylated naphthalenesulfonic acid (sodium salt);di(2-ethylhexyl)ester of sodium sulfosuccinic acid; sodiumalkylnaphthalenesulfonate; sulfonated monoglyceride of coconut fattyacid (sodium salt); polymerized alkylated arensulfonic acid (sodiumsalt); sodium oleyl sulfate; sodium lauryl sulfate; sodiumoleylisethionate; sodium dibutylnaphthalenesulfonate; sodium dodecylbenzenesulfonate; or sulfonated alkylbenzimideazole (sodium salt); andthe like. These surfactants are added in amounts sufficient forsubstantially all of the cells to dissolve and release the viscosifier.This amount is dependent upon the surfactant that is used.

In order to provide a resultant aqueous driving fluid that increases inviscosity at desirable rates, it is preferred that the pH of thebacterial cellular solution be adjusted to have a pH of about 7.5 aftermixing the formaldehyde therewith. This pH adjustment can convenientlyand acceptably be accomplished by adding one normal sodium hydroxide forexample to the bacterial solution. It is also preferred to likewise andfor the same reason adjust the pH value of the formaldehyde andbacterial solution mixture to a valve within the range of about 6-12.This pH adjustment can conveniently and acceptably be accomplished byadding to the formaldehyde and bacterial solution mixture materialsselected from the group comprising water, an alkali such as sodiumhydroxide, or mixtures thereof.

Other desirable flooding materials such as antioxidants, for example,can also be added to the flooding medium of this invention.

The desirable initial, intermediate, and final viscosities of theaqueous driving fluid are dependent upon the flooding and formationconditions and are values that can be routinely selected by one skilledin the art such as a petroleum engineer.

The following are stability tests run on various mixtures showing theeffect of formaldehyde on the viscosity of bacterial preparations. Thesetested materials were formed from samples of a single bacterial solutionhaving a pH of 7.5 and comprising pseudomonas type organisms grown onmethanol. Viscosity measurements were made on a Fann N-G ViscometerModel 35 at 300 r.p.m. at room temperature of about 72 F. with a 300 cc.sample volume. These viscosity measurements were taken initially on eachsample and thereafter at 5, l0, and 15 day intervals. The HCHO added wasfrom a 37 percent formaldehyde solution and the volume of cells on a dryweight basis was 25 g. per liter ofthe solution.

TABLE volume of formaldehyde,

thereafter adding an anionic surfactant to the bacterial cellularculture andformaldehyde mixture, said anionic surfactant being added inamount substantially sufficient to dissolve said bacterial cells, and

wherein the pH of said aqueous medium driving fluid is adjusted to a pHrange of about 6 to 12.

2. A process, as set forth in claim 1, wherein the bacterial cellularculture comprises up to about 4 weight percent whole bacterial cells.

3. A process, as set forth in claim 2, wherein the bacterial cellularculture and formaldehyde mixture, or the admixture thereof with saidanionic surfactant, is adjusted to have a pH of about 7.5.

4. A process, as set forth in claim 1, wherein the volume of theformaldehyde employed is in the range of about 0.1 to 5 weight percentof the bacterial cellular culture.

5. A process, as set forth in claim 4 wherein the anionic surfactant isadded to the bacterial cellular culture and formaldehyde mixture about 5minutes to 24 hours after forming the bacterial cellular culture andformaldehyde mixture.

6. A process, as set forth in claim 5, wherein the pH of the FaunVisccmetertModel 36, readings a 10 16 Sample composition 1 time daysdays days 1. 100 cc. cell sol.+1% ECHO-H00 cc. tap water+ pH to 11+4%NaLS 11 51 43 43 2. 100 cc. cell sol.+200 cc. tap water+1% HCHO-ipH to11+0.4% NaLS 12. 6 32 17 10 3. 100 cc.+200 cc. tap water-l-pH to 11+1%HOBO-+0.04% NaLS 52 23 17. 6 16 4. 100 cc. cell s0l.+200 cc. tapwater-l-pH to 11+ 0.4% NaLS+1% HCHO 53 53 29 16 5. 100 cc. cell sol.+1%HGHOI-pH to 11+2Q0 cc.

tap water+0.4% NaLS 9. 5 47 43 46 6. 100 cc. cell sol.+pH to 1l+200 cc.tap water-{- 0.4% NaLS+1% HCHO 38 28 23 7. 100 cc. cell sol.+1% ECHO-+0.1% NaLS+200 cc. tap water+pH to 11 10. 5 72 B3 63 8. 100 cc. cellsol.+0.4% NaLS-l-ZOO cc. tap water+ pH to 11+1% HCHO 41 34 26 18 9. 100cc. cell sol.+1% HCHO+200 cc. tap water+ pH to 11 7. 6 22. 5 113 12 10.100 cc. cell s0l.+200 cc. tap water+1% HCHO+ pHto 11 7.5 18 7.5 11. 100cc. cell sol.+200 cc. tap water-l-pH to 11+ 1% H0110 62 50 12.5 12. 100cc. cell sol.+1% HCHO+200 cc. tapwater+ 0.4% NaLS 7 21 [i6 13. 100 cc.cell sol.+200 cc. tap water+1% HCHO+0.4% NaLS 8 16 4. 6 14. 100 cc.+200cc. tap water+0.4% NaLS to 1% 1 Sample composition having componentsmixed in the order listed.

These tests indicate the addition of formaldehyde prior to 50 bacterialcellular culture and formaldehyde mixture is ad the addition of theanionic surfactant or adjustment in pH to a pH of l 1 causes a delay inthe formation of viscosity and the maintenance of the high viscosityover extended periods of time, as shown by Sample Compositions l, 2, 5,7, 9, l0, l2, and 13 of the table. Sample Compositions 3, 4, 6, 8, ll,and 14 show immediate buildup of viscosity owing to changing the pH oradding the surfactant prior to addition of the formaldehyde.

By so providing a driving fluid of this invention, fingering of thefluid within the formation is decreased while initial pumping of thefluids required lower horsepower requirements than heretofore utilizedincreased viscosity flooding fluids.

Other modifications and alterations of this invention will becomeapparent to those skilled in the art from the foregoing discussion andtable and it should be understood that this invention is not to beunduly limited thereto.

What is claimed is:

1. In a process for recovering hydrocarbons from a subterraneanhydrocarbon-containing formation by injecting therein an aqueous mediumdriving fluid through said formation to displace hydrocarbons therefrom,the improvement compris ing:

employing an aqueous medium driving fluid containing a viscosifierproduced by the action of first mixing an aqueous bacterial cellularculture comprising whole bacterial cells to the extent of at least 0.2weight percent with a justed to a value in the range of about 6 to 12.

7 A process, as set forth in claim 6, wherein the pH of the bacterialcellular culture and formaldehyde mixture is adjusted by adding to themixture water, an alkali, or mixtures thereof.

8. A process, as set forth in claim 7 wherein the anionic surfactant issodium lauryl sulfate, and said bacterial cellular culture is producedby pseudomonas type organisms.

9. The process according to claim 1 wherein the pH of said mixturecontaining said anionic surfactant is adjusted to a pH value in therange of about 6 to 12, and the pH adjustment is accomplished by addingto said mixture containing said anionic surfactant water, an alkali, ormixtures thereof.

10. A process for recovering hydrocarbons from a subterraneanhydrocarbon-containing formation by injecting therein an aqueous mediumdriving fluid through said formation to displace hydrocarbons therefrom,the improvement comprismg:

a. employing an aqueous medium driving fluid containing a viscosifierproduced by the action of first mixing an aque' s "iiridTdifialdehymixture bacterial cells, thereby producing said viscosifier 11. Aprocess, as set forth in claim 10, wherein an alkaline material is addedto said aqueous admixture prior to or subsequent to contacting saidadmixture with said anionic surfactant, and said alkaline material issufficient to adjust the pH of said admixture to a range of between 6and 12.

2. A process, as set forth in claim 1, wherein the bacterial cellularculture comprises up to about 4 weight percent whole bacterial cells. 3.A process, as set forth in claim 2, wherein the bacterial cellularculture and formaldehyde mixture, or the admixture thereof with saidanionic surfactant, is adjusted to have a pH of about 7.5.
 4. A process,as set forth in claim 1, wherein the volume of the formaldehyde employedis in the range of about 0.1 to 5 weight percent of the bacterialcellular culture.
 5. A process, as set forth in claim 4 wherein theanionic surfactant is added to the bacterial cellular culture andformaldehyde mixture about 5 minutes to 24 hours after forming thebacterial cellular culture and formaldehyde mixture.
 6. A process, asset forth in claim 5, wherein the pH of the bacterial cellular cultureand formaldehyde mixture is adjusted to a value in the range of about 6to
 12. 7. A process, as set forth in claim 6, wherein the pH of thebacterial cellular culture and formaldehyde mixture is adjusted byadding to the mixture water, an alkali, or mixtures thereof.
 8. Aprocess, as set forth in claim 7 wherein the anionic surfactant issodium lauryl sulfate, and said bacterial cellular culture is producedby pseudomonas type organisms.
 9. The process according to claim 1wherein the pH of said mixture containing said anionic surfactant isadjusted to a pH value in the range of about 6 to 12, and the pHadjustment is accomplished by adding to said mixture containing saidanionic surfactant water, an alkali, or mixtures thereof.
 10. A processfor recovering hydrocarbons from a subterranean hydrocarbon-containingformation by injecting therein an aqueous medium driving fluid throughsaid formation to displace hydrocarbons therefrom, the improvementcomprising: a. employing an aqueous medium driving fluid containing aviscosifier produced by the action of first mixing an aqueous bacterialcellular culture comprising whole bacterial cells to the extent of atleast 0.2 weight percent with a volume of formaldehyde, b. recoveringfrom said step (a) the formaldehyde treated bacterial cells from saidaqueous bacterial cellular culture and formaldehyde mixture, c. admixingsaid recovered formaldehyde treated bacterial cells with water to forman aqueous admixture therewith containing at least 0.2 weight percent ofsaid whole bacterial cells, and d. contacting said aqueous admixturecontaining formaldehyde treated whole bacterial cells with anionicsurfactant in amounts substantially sufficient to dissolve saidbacterial cells, thereby producing said viscosifier.
 11. A process, asset forth in claim 10, wherein an alkaline material is added to saidaqueous admixture prior to or subsequent to contacting said admixturewith said anionic surfactant, and said alkaline material is sufficientto adjust the pH of said admixture To a range of between 6 and 12.